Hinshaw D A, Dobbins J T
Department of Radiology, Duke University Medical Center, Durham, North Carolina 27710, USA.
Med Phys. 1996 Jun;23(6):871-6. doi: 10.1118/1.597855.
We have developed a method for correcting for the scatter produced by the computed radiography plates in single-shot dual-energy imaging. In our technique, which uses a series of four computed radiography plates (the middle two plates act as a filter), the back plate can have scatter fractions as high as 30% due to the scatter from the first three plates. We use the deconvolution method to correct for this scatter, as the scatter medium is uniform and isotropic with a constant air gap. The ratio of the modulation transfer function (MTF) of a standard computed radiography plate to that of a dual-energy plate gives us the correction factor we need to scale the Fourier transforms of our images, thus compensating for the reduced response of the system due to scatter. We also investigated the effect of having an air gap between the back dual-energy plate and the first three plates. Our measurements show that this degrades the signal-to-noise response of the back plate slightly at low spatial frequencies. We also used independent scatter fraction measurements to verify the validity of our MTF measurements. Applying the correction to a back plate image improves the fine detail contrast by approximately 30%.
我们已经开发出一种方法，用于校正计算机X线摄影板在单次双能成像中产生的散射。在我们的技术中，使用了一系列四块计算机X线摄影板（中间两块板用作滤波器），由于前三块板的散射，后板的散射分数可能高达30%。我们使用去卷积方法来校正这种散射，因为散射介质是均匀且各向同性的，并且具有恒定的气隙。标准计算机X线摄影板与双能板的调制传递函数（MTF）之比，为我们提供了对图像傅里叶变换进行缩放所需的校正因子，从而补偿由于散射导致的系统响应降低。我们还研究了后双能板与前三块板之间存在气隙的影响。我们的测量表明，在低空间频率下，这会使后板的信噪响应略有下降。我们还使用独立的散射分数测量来验证我们MTF测量的有效性。对后板图像应用校正可将精细细节对比度提高约30%。
